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本帖最后由 huajiji 于 2010-4-27 17:03 编辑
在光盘的test程序里面,keyscan.c文件里面有KeyScan_Test()函数,里面有个关于外部中断的语句我不是很懂:
pISR_EINT0 = pISR_EINT1 = pISR_EINT2 = pISR_EINT4_7 = (U32)Key_ISR;
Key_ISR是中断函数,返回值是空类型的,怎么可以强制转化为U32类型呢?还有pISR_EINT0 ,pISR_EINT1, pISR_EINT2 ,pISR_EINT4_7 ,是不同的中断向量,又怎么能让它们相等呢?有什么意义呢?
下面是Key_ISR()和KeyScan_Test()的源码:
static void __irq Key_ISR(void)
{
U8 key;
U32 r;
EnterCritical(&r);
if(rINTPND==BIT_EINT1)
{
//Uart_Printf("eint1\n");
ClearPending(BIT_EINT1);
}
if(rINTPND==BIT_EINT4_7)
{
ClearPending(BIT_EINT4_7);
if(rEINTPEND&(1<<4))
{
//Uart_Printf("eint4\n");
rEINTPEND |= 1<< 4;
}
}
if(rINTPND==BIT_EINT0)
{
//Uart_Printf("eint0\n");
ClearPending(BIT_EINT0);
}
if(rINTPND==BIT_EINT2)
{
//Uart_Printf("eint2\n");
ClearPending(BIT_EINT2);
}
key=Key_Scan();
if( key == 0xff )
Uart_Printf( "Interrupt occur... Key is released!\n") ;
else
Uart_Printf( "Interrupt occur... K%d is pressed!\n", key) ;
ExitCritical(&r);
}
void KeyScan_Test(void)
{
Uart_Printf("\nKey Scan Test, press ESC key to exit !\n");
rGPBUP = rGPBUP & ~0x03f0|0x03f0; // LED [8:5] => PU En
rGPBCON = rGPBCON & ~0x3d57fc|0x3d57fc; //LED[8:5] => OUTPUT;
rGPFCON = rGPFCON & (~((3<<4)|(3<<0)|(3<<8)|(3<<2))) | ((2<<4)|(2<<0)|(2<<8)|(2<<2)) ; //GPF4,2,1,0 set EINT
rEXTINT0 &= ~(7|(7<<4)|(7<<8)|(7<<16));
rEXTINT0 |= (0|(0<<4)|(0<<8)|(0<<16)); //set eint0,1,2,4 falling edge int
rEINTPEND |= (1<<4); //clear eint 4
rEINTMASK &= ~(1<<4); //enable eint 4
ClearPending(BIT_EINT0|BIT_EINT1|BIT_EINT2|BIT_EINT4_7);
pISR_EINT0 = pISR_EINT1 = pISR_EINT2 = pISR_EINT4_7 = (U32)Key_ISR;
EnableIrq(BIT_EINT0|BIT_EINT1|BIT_EINT2|BIT_EINT4_7);
while( Uart_GetKey() != ESC_KEY ) ;
DisableIrq(BIT_EINT0|BIT_EINT1|BIT_EINT2|BIT_EINT4_7);
} |
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